Fractional skin resurfacing or rejuvenation is a recently developed skin ablative technology. There are two types of devices used to ablate the skin: laser based devices and RF based devices. Both types of these devices ablate a pattern of extremely small diameter shallow holes or zones. The holes are microscopically small treatment zones surrounded by untreated skin areas. The treatment results in a very rapid healing or recovery and skin resurfacing of the treated. In the healing process of the treated zones, a layer of new skin appears, restoring a fresh, youthful complexion.
The pattern of small holes is typically produced by an X-Y scanning laser beam or by application of RF energy or voltage. The laser is focused on the skin and usually operates in pulse mode ablating micron size holes in the skin.
RF based fractional skin treatment produces a scanning pattern of micron size holes in the skin a similar to laser. Typically, the energy is delivered to the skin by an applicator equipped by a tip having a plurality of voltage to skin applying/delivering elements or contact elements arranged in a matrix or in an array. The voltage to skin applying elements are placed in contact with the segment of the skin to be treated and driven by a source of suitable power and frequency RF energy. Application of a high voltage RF pulse to the electrodes ablates the skin under the respective electrode forming a small hole.
In some instances application of laser or RF voltage pulses causes discomfort and even pain to the treated subject, although the experience based on the individual and as such, the pain sensation may be different from subject to subject. In other instances there may be a difference in the size of micro holes formed by the applicator at the same treatment session. Healing of larger size holes may take a longer period of time than the healing process for smaller size holes and in some instances, the larger holes may tend to result in causing damage to the skin rather than producing the desired skin effect.
In order to soften the discomfort and lessen the pain and other side effects associated with the fractional treatment, practitioners have started using topically applied lidocaine cream or even oral sedation.
Fractional skin treatment is applicable in the correction of almost all cosmetic skin defects such as signs of aging, wrinkles, discolorations, acne scars, tatoo removal, and other skin defects. The cost of the RF based products is lower than that of the products operating with laser radiation and they will most probably become widely used if the discomfort and occasional pain associated with their use could be eliminated.
US Patent Application Publication No. 2006/0047281 and U.S. patent application Ser. No. 12/324,932 to the same assignee disclose RF based products such as eMatrix™ suitable for fractional skin treatment.
Glossary
In the context of the present disclosure “RF voltage” and “RF energy” are used interchangeably and have the same meaning. The mathematical relationship between these two parameters is well known and knowledge of one of them allows easy determination of the other.
In the context of the present disclosure “skin resistance” and “skin impedance” are used interchangeably and have the same meaning. The mathematical relation between these two parameters is well known and knowledge of one of them allows easy determination of the other.
The term “desired skin effect” as used in the present disclosure means a result of RF energy application, which may be wrinkle removal, hair removal, collagen shrinking or destruction, skin rejuvenation, and other cosmetic and skin treatments.
The term “plateau” of a function is a part of its domain where the function has constant value.